Gas burner



Feb. 21, 1933. A U WETHERBEE 1,898,799

GAS BURNER Filed July 2l, 1927 2 Sheets-Sheet l Feb. 21, 1933.

A. U. WETHERBEE GAS BURNER Filed July 21, 1927 Mm @f7 2 Sheets-Sheet 2Patented Feb. 21, 1933 UNITI-:u STATT-:s

PATENT lori-Ica ASHUR 'U'.WIBTHERBE OF EVANSTON, ILLINOIS, ASSIGNOR TOAUTOGAS CORPORATION, F CHICAGO, ILLINOIS, A CORPORATION OF`DELAWARE GASBURNER Application mea my 21, 1927. serial No. 207,399.

My invention relates to combustion of gaseous fuel, and the object ofthe invention is, broadly, to provide a more economical method ofdeveloping the heat generated by combustion ofV a gaseous fuel.

Vhile throughout the specification an claims herein I refer to the fuelas gas o r as being gaseous, I do not intend to limit the invention tothe burning of a fixed gas, as the principles of the invention and thestructural features herein disclosed are applicable to the combustion ofany fuel of suiicient IinenessV that it acts substantially as a gas,that is, either vaporized, atomized, or pulverized to a degree where itscombustion is capable of occ'urring with 'substantially explosiverapidity.

The specific problem which I-'have set out to solve is the provision ofmeans and a meth-y od for burning city gas with high economy of heatdevelopment and transfer, and having the ability to stop and startoperation of the burner with ease and certainty.

Where known methods of utilizing gas combustion for house heatingservice .have been employed, the cost has generally been excessive ascompared with the cost of other fuels.

This is particularly'true in connection with known types of steam or`hot water systemsl which have been worked out in connection with thecombustion of solid fuel. It has been a generally. accepted fact thatwith known types of steam or hot water boilers or furnaces, thesubstitution of gas fuel for the solid fuel, for which such boilers orfurnaces were designed, has been out of the question because 'ofineliieiency and consequent excessive cost. v f

I have studied the problem and come to the conclusion that the reasonfor this is largely chargeable to the involved.

In the combustion of solid fuels there is always a mass of incandescentsolid f uel which radiates heat. Where gas is'burned in the Bunsen typeof burner, the flame, although short, has'very small heat radiatingpower. VIt appears to be a known fact that radiation from a given massis a function of 59 tempera-ture of that mass and other character-`method `of heat transfer istics thereof. According to y the law ofStefan and Boltzman, radiation of heat from a given mass isapproximately proportional to the difference between the fourth power ofthe absolute temperature of the heated massand the temperature of thelreceiving surface. l

I have therefore taken, as the primary consideration in my invention,the possibility of transferring the heat from the combustion of the gasto the boiler walls by employing a mass of suitable character involvingthe maximum amount of heat radiation.

As ameans for providing the incandescent mass, I employ a mass ofrefractory of large superficial surface and of a loose granular orforaminated struc ure. In the preferred embodiment later to bedescribed, I utilize' relatively thin flat chips of fire-brick laid on asolid base of refractory, The mass of loose refractory is heated by thecombustion of gas within the body of the same.

I am aware of the employment of a'somewhat similar scheme of combustionwithin a mass of loose refractory, material originally patented byLucke, but, as I shall point out later, there are very important andessential differences between my method and that of the prior art. I amalso aware of the use ofv targets against which ablast burner isdirected for the production of a radiating mass.

As I shall point out later, there lare serious objections to the use ofsuch a method of combustion in the service in which my invention isparticularly useful, namely, domestic heating.

For the development of maximum temperature'of the mass, the heat of theame y must be as great as possible.y Ton this end no i excess airshouldbe admitted and, at the same time, .no unburned fuel should bepassed out of the stack inthe interest of economy, Itis one of theessentials ofmy invention that there must be as complete mixing of thegas and supporting air as possible.

For house heating service, t/heeombustion should be capable of automaticcontro1,i. e., preferably oif and l on, or, alternatively, up and down?,and, above all, there/ must be no danger ,of explosion at any time, no'r10 should there be any appreciable explosive puff when the burner comeson after being shut ofi', or when the burner is shut olf after anoperation. Likewise, the burner must be so constructed that the flamecannot strike back into vany confined space, both because of danger ofexplosion and because of danger through an orificeat such velocity thatstrikj ing back is not possible. I have tried flame arresters in theform of screens.

proven impracticable.

Y through a mass of refractory and project the According to my inventionI employ only a thin bed of refractory of small mass supported on a bowlor plate of solid refractory,

which, at the same time, serves both as a nonconductor of heat and as arefiector of the heat of the mass of broken refractory. vI pass theflame or burning gases edgewise through this mass of loose refractoryand carry on combustion at a high rate, i. e.,-- at substantially anexplosive rate. The mass of loose refractory becomes incandescent andthe radiation of heat occurs from the lateral face of the bed, i. e.,from the exposed upper surface. The propagation of heat rays istherefore at substantially right angles to the general direction'of theburning gases. By this means only a small mass needs to be heated up tostart and a largev radiating surface is provided. This 'great ratio ofradiating surface to mass permits of a much greater rate of fuelcombustion within a given space than has, been possible heretofore.Overheating of any part of the mass is preventedfy By propagation ofheat radiation from the side or Hank of the path of gas travel, thelength of the fiame is not of importance.

I am aware that it is old to fire upward heat in the same direction, butthe prior art has this inherent defect', namely, that the central innerpart of the mass attains a high degree of incandescence which canradiate only through interstices of the upper layers. The top layers arean` effective barrier to radiation from 'the central mass.l The majorparts of the combustion is at the center and, hence, the top layers,from which effective radiation must occur, if'at all, are unheated bydirect contact with the fire. If the input ofl cblmbustible-material istoo great, then burning over the mass occurs. If the input is too small,the fire occurs wholly inside the.

m'aarrdrthetepllayer effectively prevents radiation.

They have with the accompanying drawings which illustrate an embodiment`of my invention.

Inthe drawings 1 v Fig. 1 is a plan `view of a burner embodying myinvention;

Fig. .2 is a vertical section taken on the line 2-2 of Fig. 1 shown onan enlarged scale; and

Fig. 3 is a similar section through a portion of a'modification. j

Referring now to Figs. 1 and 2, I provide a bowl l, which is preferablyconstructed of sections. This bowl is made of fire-brick of high heatresisting and insulating properties. The sections are provided'withoverlapping joints 2--2 so as to prevent an 'open crack where thesections come together.

eol

This bowl constitutes, inreality, a plate or disc of refractoryinsulating material for radiating the heat developed by the gascombustion upwardly and for preventing' the travel of heat theredeveloped downwardly through the mass of the same.

' The section 3 contains, a recess- 4 in which there is disposed asparkplug 5, the metallic shell of which is suitably grounded and thecentral electrode of which is connected through suitable controlapparatus with a source of high tension current. l

I have, for the sake of clearness, omitted from the present disclosurethe control apparatus, reserving the same for a later application. r

The electrodes of the spark plug are so disposed with respect to thepath of gas travel as to be capable of igniting the combustible mixturereadily.

The bowl or disc 1 is seated on a. supportflanges 9 at their lower endsand having-their upper ends disposed inpockets-10 and-.en-

gaging the lugs 11 through the medium of a threaded nut 12 by which theheight of the posts may be adjusted.

and are apertured to receive thev clamping bolts 13 for clamping themixer 14 `to the frame. 4

The mixer 14 comprises an outer gas chamber 15 and an inner air passage16 within which is disposed a helical directing vane 17 for producing awhirling action of the air y passing through the passagel. The lower Thelugs 11 on the ring 6 extend inwardly elbow 19 to an air inlet pipe 20,this pipe 20 in present case, are 45 degree Ls, with the gas end of themixer 14 comprises a cylindrical threaded extension 18 connected by apipe turn leading to the delivery of a fan or blower (not shown). Thegas chamber communicates through a hollow lateral boss 21 and pipeiittings 22-23, which latter, in the inlet pipe 24. The air pipe 2() isprovided wlth a throttle valve 25 and the gas pipe 24 1s provided withasimilar throttle valve 26,

, these two valves being connected by a stem 27 and having a suitableopeiating. handle 28 for simultaneous adjustment. The gas pipe 24 leadsto the cit main through a pressure regulator, prefer-abb for holding thegas pressure substantially A constant at all times. It is apparent thatthe butterfly valves 25 and 26 may beI independently regulated, butafter the pressure' regulator for the gas has been suitably adjusted tothe delivery of the blower connected to the air pipe 20, a simultaneousadjustment of air and gas, such as is possible by the butterfly valves25--26, is desirable. f

The gas chamber 15 empties into the air passage 16 above the vane 17through a slot 29. The gas and air then proceed from the outlet of themixer 14 through a short passageway 30, which passageway is, in the formshown in Figs. 1 and 2, provided as a central aperture in adisc or plate32 of firebrick, let into a recess or counterbore in the bowl orplate 1. The mixer 14 extends up through the central opening 3 2 whichis formed in the ,disc or bowl 1. J

The opening 30 in the disc 32 is covered by a cap 33 of hre-brick orlike material, supported on a central spider 34,=which spider has aseries ofdirecting vanes preferably, but not necessarily, helicallydisposed in a direction opposite to the twist of the directing vane 17.The spider 34 is conically formed at its lower end to seat inthe conicalupper end of the opening 30 for centering these two parts with respectto each other. The cap 33 i 1s preferably cemented tothe spider 34 sothat the lower edge of the cap 33 is held a fixed distance above theplate 32 to provide a Aperipheral slot or outlet 35 around the peripheryofthe cap 33.

Along its outer margin, where the plate 32 comes flush with the surfaceof the bowl or disc 1, I provide a series of projections disposed ashort distance from the rim of the cap 33. Flat chips 36 of {ire-brickrest at their inner edges against the capv33 and are supported away fromthe surface of the disc 32 and bowl 1 by the projecting ends or projections 37.

AChips graduated in size are then laid in overlapping rings in thefashion of shingles from the central chips 3S to the outer edge ly ofthe mercury type,

In effect, the bowl 1 comprises. the central disc 32 as Well as theiouter sections. central di c' 32 is, in this'case, made of singlepiece, but' this is not essential, since, due to the great heat to.which it is subjected, it expands and contracts and tends to crack incase it is made of one piece. y

As shown in Fig. 3, I refer therefore to make the fas passages o metalthroughout until they ischarge into the zone of combustion.

It`will be seen that by disposing the coarser chips a-t the center andraising them slight- The i ly above the oor of thepbowl, a relativelyfree passageway for the mixture of gas and air is provided within thecentral part of the brick highly satisfactory, but I do' not aim toconvey the impression that other forms ofgranular material may not beused..

Theoretically,- the ideal way of making up this burner would be to havethe bowl 1 covered by a mass of checker work in a very thin v layer,preferably graduated from coarse checker work at the central part tofine checker work at the outside, and then to have a layer of somematerial, assume, for example, quartz, overlying thetop surface of thechecker work and serving to direct the gases of combustion all out tothe outerperiphery, but permitting freely of radiation fromfthe topsurface of the same. Now the construction which I have shown, namely,the flat thin chips .of refractorymaterial, that is, broken {ire-brick,serve to perform Athis function suiiiciently well t'o direct the flow ofburning gases' out along the surface of the bowl 1 so that burningoccurs within the mass of broken refractory, even though it is I.verythin, and the `heat thus developed is projected off by radiationsubstantially normal to the surface of the granular mass. It will beseen that by the shingling effect the gases are diverted downwardlytoward the surface of the bowl 1 and thereby are held more or less incontact with the same. i Y

I have tried the 'burner without the layer of granular refractory. Itwill burn gas, but two things are noticeably absent; first0nlya v erysmall amount of radiant heat will be developed; and,` next, only a smallamount 'of l gas can be burned within the bowl as compared with theamount that can be burned when the layer of loose refractory posedthereupon.

Preferably in the operation of the device,I 125 the blower is started.and the spark plug is caused to act, and thereafter the gas is admittedthrough the pipe 24. When combustible mixture reaches the spark plug, itwill be ignited and it will burn back to substantially the edge of thecap 33.

is dis- If the amount of mixture delivered to the burner is increased,the edge of the flame reaches out further towards the periphery of thebowl 1, and if the amount 'of fuel supplied is decreased then` the flamerecedes 1n thel refractory'layer towards the'cap 33,; but the size ofthe iame within the limits of the burner is immaterial, or substantiallyso for the development of radiant heat. The` amount of fuel whichcan beburned per unit of time in a burner of this character is amazing. Theefiiciency of the device as a radiator of heat is very high, because ofthe large radiating area ascompared to the volume of gas undercombustion or the volume of material which is at incandescence.

In Fig. 3 I have shown a modified form of nozzle construction. In thisconstruction the bowl 1 is made of a plurality ofsectons, the edges ofwhich overlap, as explained in connection with Figs. 1 and 2. This bowl,like'- Wise, has the central aperture 41 through which the mixture ofgas and air is delivered under the cap member which comprises a metalcap /member 42 covered with a layer or covering 43 of lire-brick or likematerial. The spider 34 may be made integral with the metal cap 42, orit may be made separately.

- The spider 34 has suitable vanes which serve both to sup-port the capand also to direct the mixture. The nozzle gap 44 is formed between twometallic surfaces, namely, the

4 viiange 45 of the cap and a companion flange 29 and the slot 35,

' combustible mixture,

until substantially the very outlet into the. Hence, in starting or 46of a neck member 47 which forms an extension of theair passageway 16above the vane 17 and the peripheral inlet 29 from the gas chamber 15. yl

I wish to call attention to the very small volume of mixture which canat any time exist between the slot 29 and the slot 44, in the form shownin Fi 3, or between the slot sfliown in Fig. 2.. The volume ofcombustible mixture is so small at any time that, even ifthe sameshouldbe ignited, no serious injury can be done, particularly in view of thefact tbatthe cap 33 or 40 is held in place `only by its own weight.

The velocity of the gases through this art of the pathis normally sogreat that com ustion does not strike back. Inaddition, mixing iscarried on in such a short space that a as such, is not attainedcombustion space? stopping combustion underk automatic control, the 'objectionable explosive start or stop of the prior art is not encountered.

Tests which I have made on this burner, in conjunction with a standardand well known cast iron boiler very widely soldfor domesticheating,.known asthe Ideal boiler, manufactored bythe Americanl RadiatorCompany, -and designed for the combustion of solid .fuels such as coalor coke, show amazingly high efficiencies.

was approximately 45 lbs., and theweight ofI the irebrick chips 5 lbs.

thick at the center and 3% thick Due to the small mass of the chips 38,and

their being spread out in a thin layer, the

appearance of incandescence was almost immediate, especially in a ringjust outside the point 37. This ring of incandescence spreads veryrapidly, and thetemperature increases rapidly, until a balance isobtained between .the heat absorbed from the combustion and thatradiated to the boiler. Numerous obser vations with a Leeds & Northupoptical .py rometer sb ow a temperatureof approximately 3000o F., orslightly more, these observations being taken through the intersticesbetween the chips. Since the points observable are those which radiateheat through the interstice, the temperature of the point seen is lessthan the majority of these surfaces, which are radiating and/orreiiecting heat back and forth between each other. It is believed thatthe temperature of thelower side of the chips approximates 3300 F., asthere are very visible evidences of the softening-of the surfaces ofthese chips now being used, which are of *the brand known as Empire,which softens at that temperature. y l

It is evident that with a single layer of chips, such as were used inthese tests, having the under side of such chips at such a hightemperature, gives a maximum of radiation to the heat absorbing surface.

Two of these tests were run in strict accordance with the code of theAmerican Gas Association, under the direction and supervision of twotechnical experts of a prominent public utility company, and with thecooperation of their laboratory in obtaining accurate determinations ofthe heating value, density, etc. of the gas used. f

In one of these tests,` the output of the boiler was 87.4% ofthe ratinggiven it by the Master Steam Fitters Code of Chiago, and an' efficiencyof 81.2% was obtained, based on the higher heating value of the gas. Inthe other test, the output of the boiler was 176.8% of the MasterSteamtters Code, and aneiiiciency of 7 6.45%.was obtained. Since verylittle type of boiler, these eiiiciencies are truly remarkable. This isespecially true when the unavoidable loss up the stack of the latentheat o f the water of formation, and the radiation to the room from isconsidered.

The average rate of lgas consumption in these tests varied from 259cubic feet per hour to 385.*cubic feet value from-523v B. t. u. to 540B. t. u. The gas pressure just outside the boiler varied convected heatabsorption is possible in this i the uncovered portions of the boiler(charged asa loss in these tests),

per hour, and its heatingx..

from a minimum'of 2.05 to '3.75" of water and the air pressure from 1.55to 3.65 of water, both being largely a function of area of passagewaysprovided andl the quantities of each required. Later experiments withlargerl pipes, etc. have burned successfully 500 cubic feet of gas perhour with the small pressures available. p

The carrying away of heat up the stack due .to excess air `was very.-little, as shown by the following analysis of the flue gases:

CO2 *13.2-* 12.0 02 `3.9 4.6 C() 0.0 0.0 Iotal 17 1 17.5

. covered.

` The sections of the bowl 1 are preferably hold by dowel pins, such 'asshown at 47 in Fig. 2 for loosely holding the parts together upon theframe ring 6. The vane member 16 is preferably formed on an increasingpitch in conical shape, and it will be observed that, in general, thecross section of the passage for the mixture of air and fuel continuesto be re- Y stricted through the outlet at 35 or 44. The

lower end of the vane member 17 comprises a ring which is set in arecess in the lower` part Y of the inixer 14 and held therein by a pin48. Instead of having the top surface of the bowl l smooth, I mayprovide the same with a series of sections which serve, in part, tosupport the chips '38.

Instead of using separate chips or granular bodies, I may form aforaminated or reticulated plate or body to be disposed upon therefractory base 3 or such formation of the upper face or portion of thebase 3 maybe made as to secure the desired structure of loose orforaminated mass within which combustion may be carried on and fromwhich heat radiation mayoccur.

I do not intend to limit the invention to the details shown ordescribed.

1. In combination, a dished plate of refractory and insulating material2a layer of.

relatively thin flat refractory bodles supported on the dished platewith their'ilat sides generally upwardly disposed, and a'central nozzleprojecting a sheet of quick burning mixture radially into the layer ofrefractory bodies.-

2. In combination, a. disc of refractory material having a centralaperture a supporting frame for said disc, a layer of granularrefractory disposed on said disc, a nozzle supported o n said frame andregistering with said aperture, said nozzle having a peripheral i outletfor discharging a combustible mixture edgewlse into said layer ofgranular refractory.

3. In combination, a thin bed of granular refractory, a supportingrefractory bowl, and

a spark plug supported on said bowl and having its sparking terminalsdisposed within said bed of granular refractory. 4. InA combination, aframe com-prising a ring member having supporting means therefor, anozzle member having inlets for gas i and air and a short dischargepassageway terminating in a peripheral slit, a segmental disc ofrefractory material supported on said.

ring member, said disc being apertured at its 35 center and surroundingsaid nozzle, said nozzle having a cap member -comprising refractorymaterial and 'a thin. layer of overlapping refractory chips disposed onsaid disc in register with said peripheral slit.

terial, a central stationary nozzle comprisingv a stationary cap, meansfor profecting a thin sheet of combustible mixture out radially 90 5. Incombination, a bowl of refractory mafrom under the edge of the cap, anda layer of refractory chips on said bowl.

6. In combination, a supporting frame, a facing ofl refractory materialcomprising a bowl, central inlet means lfor a combustible mixture, a capover said inlet means providing a discharge slot below the cap betweenits rim and the bowl, and a layer of refractory chips on said bowloverlying the edge ofthe cap. 7. In combination, a supporting framehaving a refractory facing forming a bowl, and a layer of refractorychips on the surface of said bowl, said chips being of graduated litnessfrom the central partfof the bowl to the rim thereof the top of thelayer being subl stantially bowl shaped.` ,p

8. In combination, a supporting frame having a refractory facing forminga bowl, a layer of refractory chi s on the surface of said bowl, andmeans for ischarging substantiallyf all of a fast burning mixture fromthe central part of the bowl outward towards the rim through said layerof chips. y

9. In a burner, the combination of a. bowl having a central aperture, acap covering said aperture, a layer of refractory materialv in the bowlextending from the cap to the periphery, a supportingspider between thecap and the bowl, and a gas-airmixer having a discharge port leadingthrough the spider under said cap.

10. In a` radiant heater, a thin laye-r of pieces lof refractorymaterial, andcentrallyW located means for projecting a blast of acombustible mixturelin the form of a sheet moving 'through andsubstantially along the layer of refractory material.

1l. In combination in a radiant heater, a plate of refractory material,a plurality' of refractory members inclined to the plate with theirlower ends in contact therewith and their upper ends spaced above theplate, saidl members being disposed in overlapping relaxtion anddefining a substantially continuous sheet of refractory material, andmeans for projecting a burning mixture in a sheet edgewisebetween theplate and said refractory sheet, the inclined under faces of 'therefractory members acting toI deflect the burning mixture downwardlytoward the plate,and away from the upper face of the refractory sheet.

l2. In combination ina radiant heater, a plate of refractory material, arelatively thin sheet of-refractory material s aced from the plate andcomprising a plura 1ty of elements disposed in overlapping relation, theplate and the sheet defining a passage therebetween for flow of aburning mixture therethrough, and means for projecting a burning mixturethrough said passage and along the inner face of the sheet for heatingit to incandescence. A

13. In combination in a radiant heater, a thin sheet of refractorymaterial comprising a plurality of elements disposed in overlapingrelation, and means for projecting a urning mixture along one face ofthe sheet and -in contact therewith for heating the .sheet toincandescence, the other face ofthe sheet acting to radiate the heattherefrom.

14. A burner comprising la base of heat resisting material, a series ofsuperim osed rel fractory elements surmounting said ase and arranged ina single layer defining one side K of a combustion space and withinterst1es between adjacent elements opening directly mto said space,and means for introducing a combustible mixture between said base andsaid refractory elements and burning it in said interstices and saidspace.

15. A burner comprising a base of heat resistng material having a'central opening, a serles of superimposed refractory elementssurmounting said base and arranged in a smgle layer defining one side ofa combustion space vand with interstices between adjacent elementsopening'directly into said space, and means arranged in said centralopening for introducing a combustible mixture between said base and saidrefractory elements and burning it in said interstices and said space. i

In witness whereof, I hereunto subscribe my name this 16th/day of July,1927.

ASHUR U. WETHERBEE.

